Created Via AND

$meta_query = array(
	'relation' => 'OR',
	array(
		'key'     => '_created_via',
		'value'   => 'test',
		'compare' => 'NOT EXISTS',
		'type'    => 'CHAR',
	),
	array(
		'relation' => 'AND',
		array(
			'key'     => '_created_via',
			'value'   => 'val1',
			'compare' => '!=',
			'type'    => 'CHAR',
		),
		array(
			'key'     => '_created_via',
			'value'   => 'val2',
			'compare' => '!=',
			'type'    => 'CHAR',
		),
	),
);