Query posts and custom post types within the same category

It sounds like all you need to do is specify the 'post_type' argument which is only 'post' by default.

$posts = get_posts( array(
    'category' => 16,
    'post_type' => array( 'post', '{another_post_type}', '{another_post_type}', '{another_post_type}' )
) );

You might also consider using WP_Query to make a custom loop instead. That’s a bit personal preference but is probably the best practice for what it looks like you’re doing.