Determining Lead Origin

Even with a thorough multi-touch attribution process like Michael suggests — and you absolutely should implement one — you won’t have “the Google ad word” in a field. This data is not passed verbatim from Google for privacy reasons. You’ll have the gclid, which you pass to Google to close the circle on attribution but which is meaningless on its own.

This depends on how you have set up your lead capturing process. How you handle Lead Source/Person Source, whether or not you save utm parameters in fields on form submit or which native integrations - e.g. with LinkedIn - you have. I think you will need to explain all that a little more to enable us to give a solid response.

If you don't know all that much about your instance, probably start with a Smart List filter like this:

Does this return any people? And if so, take a look at their activity history and and check their "filled out form" details. Which form were they submitting, how do the query strings look like and did you save them? That might enable you to add the correct fields to your reporting views or define your custom columns.