RAIN-X .
Is your friend .
The original kind that you apply to your windshield with a cloth .
I use the common blue paper/cloth shop towels on a roll available everywhere to apply .
I can drive in a heavy downpour without using the wipers as long as I keep the speed above 45 .
The water runs off the windshield .
I see the oncoming drivers with windshield wipers going full speed that have "streaky " windshields that cannot see .
I can use the slowest intermittent setting and see much better .
I know you need to fix your wipers but rain-x will work so well that it will lower the threshold as to how good your wipers are .