Taxonomies query
$featured = array( 'relation' => 'AND', array( 'taxonomy' => 'category', 'terms' => '3', 'field' => 'term_id', 'operator' => 'IN', 'include_children' => true, ), array( 'taxonomy' => 'featured_on', 'terms' => '16', 'field' => 'term_id', 'operator' => 'IN', 'include_children' => true, ), );