meta query

$meta_query = array(
	'relation' => 'AND',
	array(
		'key'     => 'user_mailster',
		'value'   => '$user_id',
	),
	array(
		'key'     => 'group',
		'value'   => '$group_name',
	),
	array(
		'key'     => 'campaign',
		'value'   => '$campaign_id',
	),
);