Which table are you referencing?
Looking at a previous example I have used when referencing the alm_asset table, I set the variable attributes to be: ref_auto_completer=AJAXTableCompleter,ref_ac_columns=asset_tag;assigned_to,ref_ac_columns_search=true
This adds the Asset Tag and Assigned To information within the results, and enables the user to search for the display name, asset tag, or the assignee to help filter the results. For example:
