$form['filter'] = array(
  '#type' => 'fieldset',
  '#collapsible' => TRUE,
  '#collapsed' => FALSE,
  '#title' => t('Filtres')
);

$form['filter']['filter_mail'] = array(
  '#type' => 'textfield',
  '#title' => t('Email'),
  '#size' => 15,
);
$form['filter']['submit'] = array(
  '#type' => 'submit',
  '#value' => t('Filtrer'),
  '#submit' => array('modulename_people_search_submit'),
);

// BUILD HEADER ARRAY
$header = array(
    array('data' => t('Nom'), 'field' => 'nom.field_profile_nom_value'),
    array('data' => t('Prénom'), 'field' => 'prenom.field_profile_prenom_value'),
    array('data' => t('Email'), 'field' => 'u.mail'),
);

// BUILD QUERY
$query = db_select('users', 'u')->extend('PagerDefault')->extend('TableSort');

$query->leftJoin('field_data_field_profile_nom', 'nom', 'u.uid = nom.entity_id');
$query->leftJoin('field_data_field_profile_prenom', 'prenom', 'u.uid = prenom.entity_id');

$query->condition('u.uid', 0, '>');

// GET CONDITIONAL FILTER VALUE
if(isset($form_state['filters']['mail'])) {
  $query->condition('u.mail', '%' . db_like($form_state['filters']['mail']) . '%', 'LIKE');
  $exportMail = $form_state['filters']['mail'];
}

// FIELDS
$query->fields('u', array('uid', 'mail', 'login', 'status'))
->fields('nom', array('field_profile_nom_value'))
->fields('prenom', array('field_profile_prenom_value'));

// GET RESULTS
$result = $query->limit(30)->orderByHeader($header)->execute();

// BUILD DATA ARRAY
$rows = array();
foreach($result as $data){
    $rows[] = array(
                $data->field_profile_nom_value,
                $data->field_profile_prenom_value,
                $data->mail,
            );
}

// ASSEMBLE DATA IN TABLE
$form['table'] = array(
  '#theme' => 'table',
  '#header' => $header,
  '#rows' => $rows,
  '#empty' => t('Aucun résultat.')
);

// ADD PAGER
$form['pager'] = array('#markup' => theme('pager'));
return $form;

function modulename_people_search_submit($form, &$form_state) {
  $form_state['filters']['mail'] = $form_state['values']['filter_mail'];
  $form_state['rebuild'] = TRUE;
  }