import os

import MySQLdb

user = 'root'
passwd = 'TOPSECRET'
database = 'mydb'

db = MySQLdb.connect(user=user, passwd=passwd, db=database)
c = db.cursor()
c.execute("show tables where tables_in_" + database + " like 'hello%'")
result = c.fetchall()

tables = ' '.join(row[0] for row in result)

sql = 'mysqldump -c -u %s -p%s %s --tables %s > custom.sql' % (user, passwd, database, tables)
os.system(sql)
c.close()