Substring a user entered varchar

I want to be able to substring a varchar that my user enters in the Power BI service. For example, my user enters in a 9 character varchar and I only want to extract the 2nd, 3rd, and 6th character in the string. This is because, my source data only has three characters which represents the 2nd, 3rd, and 6th characters. My end users are not aware of the formatting of the source data and they will only continue to copy/paste in the entire 9 character values into the 'text search slicer' and receive a 'no hit'. However, they expect relavant information to be presented in a table. Any thoughts/suggestions would be greatly appreciated!