Filter by usermeta?

Hi,
First of all thanks for this awesome plugin!
I am looking for one addition though.
Would it be possible to enable a usermeta filter as well? Now all i see is a postmeta filter, but these posts are attached to users and their meta as well right?

So in short, is it possible to implement an extra search filter for user_meta keys?

Thanks

https://wordpress.org/plugins/ultimate-wp-query-search-filter/