Search and filter for group custom fields

Hi, I was wondering if it is possible to set up a search and filter tool that will operate on group custom fields. For our site, we need to create a directory of groups (called "projects" for our purposes) but we need more than just filtering by category. We need our users to be able to filter by custom fields we have set up for each group, along with a search by keyword. I know advanced search exists, but it only works for user profiles. We need to be able to do something similar for groups.

Unfortunately, this is an absolute requirement for our site. I'm happy to do some in depth customization, but I'll need to make sure this is actually possible with ES or else we'll have to look elsewhere. Perhaps duplicating the advanced search but customizing it to work with groups would be one way to go? Any suggestions? Thanks!