Update a custom field

{
    "field": {
        "type": "textarea",
        "title": "Title",
        "descript": "Field  description",
        "perstag": "Personalized Tag",
        "defval": "Defaut Value",
        "show_in_list": 1,
        "rows": 2,
        "cols": 2,
        "visible": 1,
        "service": "google",
        "ordernum": 3
    }
}

{
    "field": {
        "title": "Title",
        "descript": "Field  description",
        "type": "textarea",
        "isrequired": 0,
        "perstag": "PERSONALIZEDTAG",
        "defval": "Defaut Value",
        "show_in_list": 1,
        "rows": 2,
        "cols": 2,
        "visible": 1,
        "service": "google",
        "ordernum": 3,
        "cdate": "2018-09-25T16:06:08-05:00",
        "udate": "2018-09-29T18:23:20-05:00",
        "links": {
            "options": "https://:account.api-us1.com/api/:version/fields/3/options",
            "relations": "https://:account.api-us1.com/api/:version/fields/3/relations"
        },
        "id": "3"
    }
}