In kubernetes, I want to restrict my pod scheduling on worker node if memory utilisation of worker node goes above 50% of its capacity?

For eg: worker node(W) have 64GB of memory and 16vCPUs

resources assigned to a pod : cpu - 4 , memory- 8GB

Now only 4 pods can be scheduled on worker node(W).

How can i achieve this ?

Node affinity , node selectors or taint and tolerations do not work in this case.