What you are looking for does not exist. By far the best option is to rent a car. Dallas and Fort Worth 60 miles apart with numerous suburban cities in between. If you are going to the area recreationally, a rental car is really the only option.
If you are going for business and need to go to one specific spot, it might, repeat might, be possible to find a park near a bus line that would eventually get you to your destination, but we need much more info to help you with that. Bus service in Dallas is not like that in the eastern cities, it doesn't serve the majority of the area.