You can use following utility.
Disclosure : I developed it.
https://github.com/vishwanatharondekar/gitlab-cli
You can create merge request using this.
Some of the features it has are.
- Base branch is optional. If base branch is not provided. Current branch is used as base branch.
- target branch is optional. If target branch is not provided, default branch of the repo in gitlab will be used.
- Created pull request page will be opened automatically after successful creation.
- If title is not supported with -m option value. It will be taken from in place editor opened. First line is taken as title.
- In the editor opened third line onwards takes as description.
- Comma separated list of labels can be provided with its option.
- Supports CI.
- Repository specific configs can be given.
- squash option is available.
- remove source branch option is available.