How to generate create table script without primary and foreign key in Oracle

Question

I have lots of schemas and tables. I want to generate create script of all of my tables. I am using below statement and it is working pretty well.

SELECT DBMS_METADATA.GET_DDL('TABLE','table_name','schema') FROM DUAL

But this statement also generates all primary and foreign key scripts that belong to table. So, is there any way to not include primary and foreign keys in create table scripts