You need to download and add the ASSP assembly to your SSAS instance (instructions here: http://asstoredprocedures.codeplex.com/wikipage?title=Installation%20Instructions&referringTitle=Home) and then use the example provided in the previous link to use the Like function in your query.

Also in your query you are only defining the "Product" set and not using it in the rows so it will show everything.