Fail in sql query with or_like

I am creating an application for vehicle control with codeigniter 3.0. The SQL query I do is the following:

MODEL

private function dataParaProcedimiento($criteria){
    $this->db->select(  T_PADRON_NOMBRES    ." as nombres,".
                            T_PADRON_APELLIDO_PATERNO           ." as apellido_paterno,".
            T_TIPO_IDENTIFICACION_F_DESCRIPCION         ." as tipo_identificacion,".
                            T_PADRON_DOCUMENTO          ." as numero_identificacion,".
                            T_VEHICULOS_F_MARCA         ." as marca,".
            T_VEHICULOS_F_MODELO        ." as modelo,".
            T_VEHICULOS_F_PATENTE       ." as patente,".
            T_OBLEA_F_CODIGO            ." as codigo,")      
            ->from(T_PADRON)
            ->from(T_VEHICULOS)
            ->join(T_OBLEA, T_OBLEA_F_ID_VEHICULO." = ".T_VEHICULOS_F_ID_VEHICULO)
            ->join(T_TIPO_IDENTIFICACION, T_TIPO_IDENTIFICACION_F_ID_TIPO_IDENTIFICACION." = ".T_PADRON_TIPO_DOCUMENTO)
            ->join(T_PADRON_OBLEA, T_PADRON_OBLEA_F_ID_PADRON." = ".T_PADRON_ID_PADRON)
            ->where(T_PADRON_OBLEA_F_ID_PADRON." = ".T_PADRON_ID_PADRON)
            ->where(T_PADRON_OBLEA_F_ID_OBLEA." = ".T_OBLEA_F_ID_OBLEA)
            ->order_by(T_PADRON_APELLIDO_PATERNO,"ASC");    

    if($criteria){
        $this->db->like(T_PADRON_NOMBRES,$criteria)
                ->or_like(T_PADRON_APELLIDO_PATERNO, $criteria)
                ->or_like(T_PADRON_APELLIDO_MATERNO, $criteria);
    }
}

VIEW

In the view I have only one inputbox ( $criteria ) to perform the search.

JavaScript

<script>
    $(document).ready(function(){       
    $("#buttonBusqueda").click( function(){
        var inputBusqueda = $('#inputBusqueda').val();
        var selectedBusqueda = $('#select_busqueda').val();
        var url = "<?=base_url('index.php/principal/buscarPersonaParaProcedimiento')?>";
                    var params = "/"+selectedBusqueda+"/"+inputBusqueda
        var winParams="toolbar=no,scrollbars=yes,resizable=yes,top=100,left=100,height=400";
        window.open(url+params,"Pop Up",winParams);
    });

    $('#popup_values').change( function() {         
        var arr = JSON.parse($(this).val());
        $('#id_entity').val(arr[0].value);
        $('#entity').val($('#select_busqueda').val());
        $('#label_data').text('Datos Asociados:');
        var contentDtDd = $('#selected_data');
        contentDtDd.html('');           
        $.each(arr, function (index, item) {
            contentDtDd.append('<dt>'+item.title+'</dt>');
            contentDtDd.append('<dd>'+item.value+'</dd>');
        });
    });     

Code to assemble the table

<?php 
$this->load->view('comun/popup_header');
$html_table_rows = "";
    foreach ($list as $item):
        $html_table_rows.="<tr><td title='Usuario:'>".$item['apellido_paterno']." ".$item['apellido_materno']." ".$item['nombres']."</td>";
        $html_table_rows.="<td title='Tipo y Nro. de Doc.:'>".$item['tipo_identificacion']." ".$item['numero_identificacion']."</td>";
        $html_table_rows.="<td title='Vehiculo:'>".$item['marca']." ".$item['modelo']." ".$item['patente']."</td>";
        $html_table_rows.="<td title='Oblea Nº'>".$item['codigo']."</td></tr>";
    endforeach; ?>

HTML

<div id="content" style="height: auto;" >    
	<div class="jumbotron" style="height: 33px;padding-top: 10px; padding-bottom: 45px;">     
        <h2 style="margin-top: 0px; text-align: center">Elegir Persona</h2>
	</div>   
	<div class="form-group">
            <div class="col-lg-12">
                <table class="table table-borderer">
                    <thead>
                        <th>Usuario</th>
                        <th>Tipo y Nro. de Doc.</th>
                        <th>Vehiculo</th>
                        <th>Oblea Nº</th>
                    </thead>
                    <tbody id="rows-selectable">
                        <?=$html_table_rows?>
                    </tbody>
                </table>
            </div>
        </div>
</div>

RESULT

When I search by name ( $criteria ), it shows me the result of the search:

PROBLEM

The problem occurs when I search by last name, which shows me the following:

When it should show me as the previous result.

Thank you!