Just committed the ability to do "full text" searching in the TACTIC expression language in 4.4 alpha.

@SOBJECT(test/type['keywords','@@','fast red car'])

This can be mixed with other search criteria:

@SOBJECT(test/type['keywords','@@','fast red car']['media_type','image'])

This will make use of the underlying database's full text search.  At present, the operator used is '@@' simply because it is used in PostgreSQL.  This doesn't seem to be a standard operator, but will work in the meantime.

Full text search had previously been implemented for PostgreSQL and SQLServer so these databases should work.