Using custom fields to store keywords

Is there a way to store keyword information in the custom fields, then when displaying an article for instance recall that to a variable. I have a function that I use to display a small column of Amazon book results related to a search query. If I do a blog on computer software, I would like the ability to put keyword for the meta and computer software in the custom field. Then when someone opens that page be able to pull that into a variable like $searchterm. Is this possible?