curl --request PATCH \
  --url https://api.example.com/v1/crm/settings/custom_fields/{id}/ \
  --header 'Content-Type: application/json' \
  --data '
{
  "key": "client",
  "name": "<string>",
  "label": "<string>",
  "placeholder": "<string>",
  "required": true,
  "table": true,
  "filter": true,
  "type": "string",
  "options": "<unknown>"
}
'

{
  "id": 123,
  "key": "client",
  "name": "<string>",
  "label": "<string>",
  "type": "string",
  "placeholder": "<string>",
  "required": true,
  "table": true,
  "filter": true,
  "options": "<unknown>"
}