You could print to a layered PDF and send this to your client. This will show the layers in your workspace, including any thematics and they'll be able to print (export).
The other alternative is MapInfo Proviwer, but you client will need to download & install this. You would then need to create a workspace, including thematic layers and send this to you client, along with ALL of the data referenced by the workspace, which may not be practical or desirable.
I will give it a go to see what would work better.