It's difficult to understand their speech and they are preschool aged (3-4 yrs old) or older.

Their speech sounds "slushy" when producing "s, z, sh, ch" sounds (at any age). 

They struggle with producing the "r" sound clearly and they are 4-5 yrs old or older.

They are pre-school aged, you notice errors in their speech production, and want to remediate it early

You are looking for a therapist who has a speciality in treating the specific area your child has needs. 

They have been evaluated previously and/or have an Individual Education Plan (IEP at school with recommended speech/language therapy services and you are interested in receiving more support toward these goals in a 1:1 setting outside of school.