<ICQL>
    <ACMP>
        <SaveSingleCustomFieldValues version="1">
            <TSaveSingleCustomFieldValuesRequest_V1 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
                <ObjectId>ObjectId</ObjectId>
        <! Possible values:
          Clients
          HDContacts
          AssetManagement
          LicenseProducts
          Licenses
          Contracts            
        >
                <QueryBase>Clients</QueryBase>
                <FieldValues>
                    <TCustomFieldValue_V1 xsi:type="TCustomFieldValue_V1">
                        <FieldId>FieldId</FieldId>
                        <Value>Value</Value>
                    </TCustomFieldValue_V1>
                    <TCustomFieldValue_V1 xsi:type="TCustomFieldValue_V1">
                        <FieldId>FieldId</FieldId>
                        <Value>Value</Value>
                    </TCustomFieldValue_V1>
                </FieldValues>
            </TSaveSingleCustomFieldValuesRequest_V1>
        </SaveSingleCustomFieldValues>
    </ACMP>
</ICQL>