Cut roast in half. Combine the garlic powder, paprika, oil, Worcestershire sauce, salt and pepper; rub over turkey. Place in a 5-quart slow cooker.
Add the garlic, ½ cup broth, water, wine or additional broth, orange juice and lemon juice. Cover and cook on low for 5–6 hours or until a meat thermometer reads 170 degrees.
Remove turkey and keep warm. Discard garlic cloves.
For gravy, combine cornstarch and remaining broth until smooth; stir into cooking juices. Cover and cook on high for 15 minutes or until thickened.
Slice turkey and serve with gravy.