How would turn a frail person in bed?

Log-roll: The best way would be to use a sheet under the patient while he/she is flat on their back. By lifting the sheet, you can roll the patient from one side to the other. Raise the head of the bed to a comfortable height when you are done.

Draw sheet: Easier way to turn someone who cannot readily do it on their own is to fold a bedsheet in thirds or quarters and put this on the bed over the bottom sheet and under the patient. Then use this like a flipper to shift the patient side to side. It supports the patient along their length without having to grab and manipulate them.