I’m trying to exclude al posts with certain meta data from the search results but so far it’s not working.
Here’s the code I’m using:

function ZoekGeenLegeItems( $query ) {
    if( is_admin() || !$query->is_search() || $query->get( 'post_type' ) != 'item' )
        return $query;

    $query->set('meta_query', array(
      'relation' => 'OR',
        array(
            'key' => 'KEY_itm_leeg'
            ,'value' => '0'
        )
    ));
    return $query;
}
add_filter('pre_get_posts','ZoekGeenLegeItems');

Any ideas, anyone?