2 schools query

$meta_query = array(
	'relation' => 'OR',
	array(
		'key'     => 'school',
		'value'   => '333',
		'compare' => '=',
	),
	array(
		'key'     => 'additional_schools',
		'value'   => '444',
		'compare' => '=',
	),
);