Get search to index meta tags keywords?
I can't check it right now, but I guess the following should work:


For each content type (its meta tags you want to be indexed), go to "Manage display". 
Add the "Search" display.
Add the metatag field to that display.


Assuming that the metatag module uses fields. If not, you'd have to create a dummy field (comment, if you need that explanation).