There are various resources in most communities that provide speech therapy for children. Speech therapy is typically only provided by a speech-language pathologist after the child has had an evaluation.
The best place to begin is to contact the child's area school district (if the child is 3 or older). If the child is under 3, contact the child's pediatrician.
Until an expert is able to evaluate and address your question, here's the link to another member's question that was similar to yours. That member received some great responses, so you might be able to find what you're looking for there.
Additionally, it would help if you provide the age of your grandchild, so that we can better target resources to assist you.
I'm lucky enough to live in a college town. The college has a speech and hearing dept that offers therapy and preschool. Your school district should have a therapist. There are many programs like first steps for younger children. Most hospitals also have therApists which could recomend someone. I hope you find a great therapist.