Steven Zahm@ andisites
This is referred to word stemming. At this time MySQL and MariaDB which is the database most web hosts use to power WP site does not support search word stemming. You would need something like Elasticsearch or Sphinx installed on you server or use a third party service to do the site indexing which supports word stemming. Neither of which is a trivial task.
A sort of quasi word stem search could be implemented but, they are resource intensive and site performance could suffer greatly. The reason is you basically would have to iterate thru the word stems performing a search for each, so a single search could go from one to 2, 3, 4 or more. That would depend on how many words the user entered into the keyword search and how many stems each of those words has.
If you are not using the Notes field, you could enter all the keywords you wish that entry to return as a result and disable search for all fields except the Notes field and perhaps a couple other important fields. Others have done that to great success in order to better control when entries surface in the search results.
Hope this helps!