This is not possible out of the box. Wasn't possible in 2010 and 2013 is no different. Sorry to be the bearer of bad news.
If you have previous versions of documents that need to be crawled and searchable, your best bet is to pull those old versions out of version history and re-submit them as "new" documents. That would get incredibly messy if your requirement included a multitude of documents, but if you only require this for a few documents, it should be doable manually.
What about a custom solution, you say? That would require creating a new crawling algorithm for SharePoint. I would say that's a nearly impossible task.
Last, consider what a mess your search results would be if SharePoint returned results from previous versions. Let's say you had 5 versions of a document. If you searched for a phrase that appeared in each version, your search query would return all 5 versions. Multiple that out across all other possible documents and you would have a lot more search results to wade through for each and every query.