Based on current system design full-text index search does not support wildcards.
https://docs.microsoft.com/en-us/dynamicsax-2012/developer/full-text-index-overview#features-and-background-information-of-full-text-search

But, we have an option to use QueryRangeType::FullText from X++ and when used, users cannot provide full memo field value for filtering and wildcards are not being supported.
It will be good to have this feature and will help in better user accessibility.