The recent blog posts widget displays posts from all public blogs which means if you just do get_post_meta() you’ll get the meta from the current blog. Not exactly what you are interested in. There’s a bp template tag to get just about everything else but the meta data. So you have to temporarily:
switch_to_blog( $post->blog_id );
$post_meta = get_post_meta(<your params>);
restore_current_blog();
Then do whatever you want with the $post_meta value you just retrieved.