Update some fields in exisiting contact

Hi guys,

I am making API call to update the contact with JSON below:

 {
                    "UID": "5f81f864-bd3a-4086-9f75-c728f194119d",
                    "LastName": "Quyet",
                    "FirstName": "Michael",
                    "IsIndividual" : true,                                     
                    "Addresses": [
                        {
                            "Location": 1,
                            "Street": "27a Commercial Rd",
                            "City": "Newstead",
                            "State": "Qld",
                            "PostCode": "4006",                            
                            "Phone1": "0411414414",                           
                            "Email": "help@thecatalysisgroup.com.au",
                            "Website": "www.thecatalysisgroup.com.au",
                            "ContactName": "Michael Quyet"
                        }
                    ],                    
                    "SellingDetails": {                       
                        "ABN" : "",
                        "TaxCode": {
                            "UID": "3bd2fbea-54d7-4115-8030-b84360048465"
                        },
                        "FreightTaxCode": {
                            "UID": "3bd2fbea-54d7-4115-8030-b84360048465"
                        }
                   },                      
                    "RowVersion": "5083169798557270016"
                }

API call: [PUT] https://ar1.api.myob.com/accountright/c06778dd-4371-4a83-975f-522df65d7574/Contact/Customer/5f81f864-bd3a-4086-9f75-c728f194119d

Yes, it will update the fields I listed on JSON. However, other fields that are not listed in the JSON, will be overwritten as empty. How can I update only the fields I listed in JSON above and keep other fields as original data?

Thanks in advance.

Micheal