CORS issue when accessing server data from localhost - .htaccess

Question

I want to access data on a remote server from a local computer via an http request. I am getting this error:
Cross-Origin Request Blocked ... Reason: CORS header ‘Access-Control-Allow-Origin’ does not match ‘[ip address].
The local machine is an angular project running on localhost:4200, the remote data is accessed via a php script located on the web (eg. https://example.com/php )
My question is: what are the appropriate header settings on my request from localhost:4200 (the client/requesting computer) and in the mod_headers section of the .htaccess file on my server (apache).
On the client side I have tried the following, where 111.111.111.111 is the IP address of the client and example.com is the domain name of the server.
headers.append('Access-Control-Allow-Origin', 111.111.111.111);
headers.append('Access-Control-Allow-Origin', http://111.111.111.111);
headers.append('Access-Control-Allow-Origin', '*')
headers.append('Access-Control-Allow-Origin', 'example.com')
headers.append('Access-Control-Allow-Origin', 'http://example.com')
On the server side .htaccess file (located in the folder of php script I am trying to launch) I have tried the following, where the 111.111.111.111 is the ip address of the machine making the request.
Header always set Access-Control-Allow-Origin "111.111.111.111"
Header always set Access-Control-Allow-Origin "http://111.111.111.111"
Header always set Access-Control-Allow-Origin "*"
Recap:
Does Access-Control-Allow-Origin need to be set on the request header, if so to what? The client's ip address? The server's ip address?
Do any other headers need to be set on the request, for example Access-Control-Request-Method?
Can an ip address be used in the server's .htaccess file or must it be a domain name? Does it need to be pre-pended with http:// or https://?