How to get search box to find image description text for Jetpack Carousel?

How can I get the search box to find the text included in the image Alt Text and Description? For example, in the search box, type in “Viggo Mortensen” and you will see “https://www.ginapiccalo.com/?s=Viggo+Mortensen” and the story “Viggo and the potato chips”, but not “https://www.ginapiccalo.com/projects/the-atlanta-journal-constitution/#jp-carousel-864” which has text in the following project: https://www.ginapiccalo.com/projects/the-atlanta-journal-constitution/

In the HEADER.PHP, I added

<div style="float: left; width: 323px;"><?php get_search_form(1); ?></div>