I think you will need the INSTR function and possibly the .IN. logical operator.
It all depends on how you are instigating the search.
If you always want to filter by a field which contains ANY of the words the approach would be different to a method which allows the operator to specify which words to use for filtering, though the core function required - INSTR() - will be the same.
Which version of Monarch do you have available?
If you have access to the Training Guide lessons 8 and 14 are probably relevent and useful.
Let us know how you get on.