Partial searches for wp_usermeta

by 

<?php
// ALWAYS sanitize user input!
$poblacion = sanitize_text_field( $_GET['poblacion'] );
$trabajo = sanitize_text_field( $_GET['trabajo'] );

$usuarios = get_users(
    array(
        'role' => 'empresa-BBDD',
        'order_by' => 'nicename',
        'order' => 'ASC',
        'meta_query' => array( // search for user meta data
            'relation' => 'AND', 
            array(
                'key'     => 'poblacion',
                'value'   => $poblacion,
                'compare' => 'LIKE' // partial comparison
            ),
            array(
                'key'     => 'trabajo',
                'value'   => $trabajo,
                'compare' => 'LIKE' // partial comparison
            )
        )
    )
);

'relation' => 'AND' is used to find users with both keys matching. Otherwise, use ‘OR’.

'compare' => 'LIKE' is the same as '%LIKE%' in MySQL, which is to say using ‘wildcards’ on both ends. Search for ’34’ will give you ’1234‘, ‘2345′ and ‘34567′.

Note! The code was not tested.