test 3
$meta_query_2 = array( 'relation' => 'OR', array( 'key' => 'ends_at_date_period_1', 'compare' => '<=', 'type' => 'DATETIME', ), array( 'key' => 'ends_at_date_period_2', 'value' => 'asf', 'compare' => '<=', 'type' => 'DATETIME', ), );
$meta_query_2 = array( 'relation' => 'OR', array( 'key' => 'ends_at_date_period_1', 'compare' => '<=', 'type' => 'DATETIME', ), array( 'key' => 'ends_at_date_period_2', 'value' => 'asf', 'compare' => '<=', 'type' => 'DATETIME', ), );