Use portainer to add a stack using file located on a git repository. It will watch for that repo for the change to the stack yaml and apply changes.
Create stacks under portainer, for each service in a stack create a webhook to update the service. From CI job make a POST request using curl to the webhook url generated on portainer.
You need your custom values.yaml containing ONLY the keys that are to be overridden. DO NOT copy full values.yaml it will be difficult to determine which key was overridden in that case just by looking at the values.yaml.
In case of pull deployment you need gitops operator like FluxCD. You will commit changes in values.yaml to a gitops repository and it will generate a release out of those values on your cluster.
In case of push deployment your CI runner has the access to you cluster and it will run helm upgrade command with changes to the overridden values.yaml available in the repo at the time of CI job execution.