How can I get all the fields and custom fields for specific issue type on Jira Service Desk API?

[Deleted user]

I've tried to so with GET request type fields but it only returns the required ones. Also I've tried your experimental method GET properties keys and it's not working. The fields I have for each issue on my Jira Service Desk are completely different to those from Jira so this method doesn't work for me either GET /rest/api/3/field. 

Many thanks in advance!