You can now create advanced search options for your members directory under MembershipWorks > Customization > Directory Search.
Search options are grouped into boxes, each search box allows visitors to search your directory by keyword, location, labels or fields. You can create multiple search boxes for different groups of labels. The new search by fields box allows your website visitors to search your members information within fields you specify, including custom fields.
Note that if your advanced search options do not appear, make sure to enable the directory search options button text under MembershipWorks > Plugin Settings (WordPress only).