Finally i got it done with Remote Action method for ToolingAPI.
id objid = '01IG0000002EHp5';//Id of the object
HttpRequest req = new HttpRequest();
req.setHeader('Authorization', 'Bearer ' + UserInfo.getSessionID());
req.setHeader('Content-Type', 'application/json');
req.setEndpoint( URL.getSalesforceBaseUrl().toExternalForm()+'/services/data/v28.0/tooling/query/?q=Select+id,DeveloperName+from+CustomField+where+TableEnumOrId=\''+objid+'\'');
req.setMethod('GET');
Http h = new Http();
HttpResponse res = h.send(req);
req.setMethod('POST');
string a = res.getBody();
list<String> lst = new list<String>();
Matcher m = Pattern.compile('"Id":"(\\w+)","DeveloperName":"(\\w+)"').matcher(a);
while(m.find()) {
lst.add(m.group(2)+':'+m.group(1));
}
Finally it returns a list with Fieldname:FieldId like below,
(Field1:00NG000000DFGuwMAH, Field2:00NG000000DFGvXMAX, Field3:00NG000000DFGvYMAX)