I would say definitely sing along to some R&B songs and practice just switching by the notes in a scale. I recently went to a voice teacher and they commented how I had vibrato and could do vocal riffs and runs naturally, as I'd been doing a lot of R&B singing since I was very young.
So, you should sing, for example, 'ah-ah-ah-ah' going up in a scale, and then faster each time. With practice, this should help you with your vocal runs. Good luck with your singing!
