How to filter by connected posts?

I have portfolios connected to services.

I want to show only the works related to services A and C. How to do that?

Surely I have to use WP_Query, but I don’t know how:

$query = new WP_Query( array(
	'post_type' => 'portfolio',
	<my filter id here> => array(
		array(
			<connected post type> => 'page',
			'value' => array( <A service id>, <C service id> ),
		)
	)
) );

http://ww.wp.xz.cn/extend/plugins/posts-to-posts/