Insert block content into the $content variable to be indexed by search
You can use Nodeblock or one of it's competitors:


  This module allows you to specify content type(s) as being a block. This allows the content managers of the site to edit the block text and title without having to access the block administration page.


Side effect of managing blocks' content like that is exactly what you want: they can be indexed in search, as they are, in fact, nodes.

If you have dynamically created blocks, you could try to use API provided by Bean module - it works the other way around, exposes blocks as entities, instead of entities as blocks. And if it will not work, well, at least you could use it as an example code for entity &lt;-> block mapping.